Even though most investigators have emphasized the role of the renin-angiotensin system in progressive renal injury, aldosterone has received little attention. However, its profibrotic effects make aldosterone a potentially important player in the field, even more so because the escape of aldosterone during treatment with ACE-inhibitors or ARBs. Moreover, in addition to these theoretical considerations, evidence is emerging that mineralocorticoid receptor blockade with spironolactone added to ACE-inhibitors or ARBs indeed has an additive, favourable effect on proteinuria. These findings warrant a search for the value of such agents in albuminuria and exploration of the mechanisms by which mineralocorticoid blockade may exert its beneficial effects.